The present invention relates to technique for reproducing or recording data from/to an optical disc.
For a medium for recording information, a magnetic tape and a disc can be given.
For the magnetic tape, a magnetic tape on which analog signals are serially recorded for a long time such as one used in VTR is well-known.
In the meantime, for the disc, an optical disc on which digital information is recorded can be given, it is used for an external storage of a computer and an apparatus for recording or reproducing an aural signal or a picture signal to/from an optical disc has been manufactured. As information can be recorded or reproduced to/from an optical disc at random, compared with a magnetic tape on which information is serially recorded, the optical disc has a merit that access to information is promptly enabled.
The above-mentioned optical disc has various types such as a compact disc (CD) and a digital video disc (a digital versatile disc) (DVD), for CD, a compact disc read only memory (CD-ROM), a compact disc-recordable (CD-R) and CD-rewritable (CD-RW) are known and for DVD, there are single-layer DVD-read only memory (DVD-ROM), dual-layer DVD-ROM, DVD-recordable (DVD-R), DVD-random access memory version 1.0 (DVD-RAM1), DVD-RAM2, DVD-RW and DVD+ReWritable (DVD+RW) (a rewritable DVD standard settled by Sony Corporation, Philips Electronics, Hewlett Packard, Mitsubishi Chemical Industries, Ltd., Ricoh Co., Ltd. and Yamaha Motor Co., Ltd. and called Phase-Change ReWritable).
As some of these plural types of optical discs are different in a method of recording and reproducing information, each optical disc is required to be switched. Therefore, the type of an optical disc to/from which information is to be recorded or reproduced is required to be discriminated.
For reference examples of discriminating an optical disc, Japanese unexamined publication No. H11-306650, No. H10-334574, No. H9-44982 and No. H8-249801 can be given.